What buffers to use for stereo in Qt using QOpenGLWidget?

I'm trying to do a stereoscopic visualization in Qt. I have found some tutorials but all of them use the older QGLWidget and the buffers GL_LEFT_FRONT and GL_RIGHT_FRONT.

AS I'm using the newer QOpenGLWidget I tried drawing images to the same buffers but the call to glDrawBuffer(GL_LEFT_FRONT) is generating a GL_INVALID_OPERATION.

I also saw that the default buffer is GL_COLOR_ATTACHMENT0 instead of GL_LEFT_FRONT so I imagine I need to use a different set of buffers to enable stereo.

Which buffers should I use?